1889 - Cicero & Proviso Street Railway Co. incorporated.
1890 - Horse car service introduced, operating in a loop via Cicero Ave., Madison St., Harlem Ave., and Lake St.
1891 - Horse cars replaced with electric streetcars.
1894 - Line completed on Chicago Ave. between Cicero Ave. and Harlem Ave., with connections via Cicero Ave. and Harlem Ave. between Lake St. and Chicago Ave.
1895 - Madison St. line extended west into Maywood.
1896 - Lake St. line extended west to Fifth Ave.
1891 - Ogden Street Railroad incorporated.
1893 - construction started on line between 40th Ave. (now Pulaski Ave.) and Lyons.
1897 - line completed to Lyons.
1895 - Suburban Railroad Co. incorporated, and begins operating a route from Cicero Ave. and Harrison St. to suburb of La Grange.
1896 - Suburban Railroad Co. leases Chicago Harlem & Batavia Railway, a steam powered commuter line owned by the Chicago & Northern Pacific Railroad Co., and with trackage utilizing Randolph St. in suburb of Oak Park. The Chicago & Northern Pacific Railroad eventually became part of the Baltimore & Ohio Railroad. Line also constructed on Harrison St. between Cicero Ave. and Harlem Ave., and south on Harlem Ave. connecting at 22nd St. with the La Grange line.
1897 - Chicago Harlem & Batavia Railway electrified, with steam trains replaced with streetcars connecting with Lake Street Elevated Railroad. Line completed on Laramie Ave. between Lake St. and 22nd St., enabling most Suburban Railroad service to connect with the Lake Street Elevated, which at the time terminated at Laramie Ave. Both the Suburban Railroad and the Lake Street Elevated Railroad were controlled by Charles T. Yerkes at the time.
1899 - Lake Street Elevated trains begin using Chicago Harlem & Batavia Railway trackage.
1903 - Chicago Riverside & La Grange Railroad formed as subsidiary of Suburban Railroad Co., owning trackage on Cermak Rd. east to 40th Ave. (now Pulaski Ave.)
1903 - Chicago Harlem & Batavia Railway route on Randolph St. abandoned. Lake Street Elevated trains meanwhile had begun using new route through Oak Park, paralleling South Blvd.
1912 - trackage within city of Chicago sold to Chicago Railways, which included Harrison St. east of Austin Ave. and Laramie Ave. north of Roosevelt Rd. Trackage in Chicago abandoned on Harrison St. between Central Ave. and Austin Ave., and on Laramie Ave. south of Harrison St. Remaining Suburban Railroad Harrison St. service abandoned.
1899 - Chicago Consolidated Traction Co. incorporated, and acquires Cicero & Proviso Street Railway Co., and Ogden Street Railroad. Chicago Consolidated Traction Co. was affilliated with Chicago Union Traction Co., and together they operated all streetcar lines on Chicago's west and north sides.
1910 - County Traction Co. incorporated, acquiring Chicago Consolidated Traction Co. trackage outside the city of Chicago. Chicago Consolidated Traction Co. had owned trackage both in the western suburbs and in Evanston.
1913 - Chicago & West Towns Railway Co. formed, acquiring County Traction Co. operations in western suburbs, and the Suburban Railroad Co. The Evanston Railway Co. meanwhile was formed to acquire the County Traction Co. operations within Evanston.
1921 - Speedway Auto Bus Co. begins operating bus route serving Hines VA Medical Center, and Northwestern Transit Co. begins operating local bus routes in Oak Park.
1924 - Chicago & West Towns Railway Co. introduces bus service over several routes.
1926 - River Forest-North West Motor Coach Co. begins operations, primarily in the suburbs of Elmwood Park, River Grove, and Franklin Park. Within a few years, company is renamed to Leyden Motor Coach Co.
1930 - Chicago & West Towns Railway Co. acquires Speedway Auto Bus Co.
1935 - Chicago & West Towns Railway Co. acquires Northwestern Transit Co.
1948 - last Chicago & West Towns Railway Co. streetcars replaced with buses.
1956 - Chicago & West Towns Railway Co. renamed West Towns Bus Co.
1963 - West Towns Bus Co. acquires Leyden Motor Coach Co.
1981 - West Towns Bus Co. acquired by Regional Transportation Authority, managed by ATE.
1985 - Pace assumes direct operation of what becomes the Pace West Division.